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We develop accurate and robust one-dimensional EXIT chart methods to design raptor codes with binary and higher-order modulations on AWGN channels over any desired range of SNRs. We formulate the check-node degree distribution optimization as a linear program that optimizes a suitable objective function of the desired operating points. The throughput curves predicted by the analysis are easily compared...
This paper examines rendezvous protocols for ad hoc network establishment in cognitive radio networks. Such capability is needed when deploying cognitive radios in an area whose existing fixed communications infrastructure has been destroyed, such as after a natural disaster. A review of previous rendezvous strategies reveals the need for more research and analysis on the multi-channel, asynchronous...
Mobile free space optical (FSO) links suffer from frequent link blockages due to opaque obstructions or link degradations that can result in degraded or failed networks. In this paper, a dynamic layer-1 based topology and routing control methodology is presented for assuring connectivity in networks with fragile links. Core components of this methodology are described with special emphasis on the...
As the world becomes increasingly dependent on dynamic and up-to-the-moment information, we recognize that broadband networks must be able to convey this information timely and wirelessly, to and from users in motion. Varieties of 802.11 compliant equipment and other types of broadband wireless equipment have been proposed for, and in some areas, being used to meet this need. There have been questions...
A future satellite communications system is envisioned that will provide a number of enhancements over predecessor satellite communication systems. It will employ high capacity packet switched service in space, high rate circuits between terminals, and utilize Dynamic Bandwidth Resource Allocation which dynamically assigns resources to terminals based on current channel conditions and traffic demand...
Certificate validation based on PKIX protocols does not work well under the particular conditions found in a MANET: Episodic connectivity and low bandwidth. We propose an overlay network of validation proxy servers which exploit cooperative caching of recent validation results. The proxy overlay improves the availability of the validation service and reduces the network traffic. The design employs...
In previous work, we proposed a ??Bootstrap?? protocol for establishing neighbor relationships, between two mobile nodes in a mission critical deny-by-default Mobile Ad-hoc Network. In this paper, we formally characterize the security properties of this Bootstrap protocol, striving to answer the following questions: 1) To what extent can an adversary undermine the correctness and performance of the...
In this paper, we highlight the impact of variable Push-To-Talk (PTT) delays on performance of a heterogeneous Land Mobile Radio (LMR) network. We first present the PTT delay values and distributions observed for some commonly used LMR nodes. An analytical model is then developed to estimate the asymmetric throughput problem. The results obtained using this model and simulations show that a LMR node...
This paper explores the robust routing of messages among individuals. Traditional routing assumes individuals provide messages to a device connected to a communications network that assumes all responsibility for message delivery. Although each individual may have links to multiple communication devices (office computer, PDA, cell phone), messages are delivered only if there is an end-to-end communication...
Recent operations in Iraq and Afghanistan have confirmed that in order to achieve effective Network-Centric Operations (NCO), innovative enhancement to military decision-making is desired. Required are processes and computational models that support the decision-makers' experience while promoting high levels of shared situation awareness (SA)-not only in the context of the external operating environment,...
The HF channel supports the wireless needs of expeditionary forces for both communication between nearby unit members (<5 km) and over-the-horizon reach-back to ship or rear base (OTH > 500 km). Cooperative communication combined with MIMO methods employing randomized space-time block coding (RST-BC) promise significant gain for over-the-horizon transmission which allows lower transmit power...
Extremely small, very low cost and very low power yet smart tactical sensors are commonly proposed. We have investigated the design patterns and algorithms that are capable of on-sensor dimensionality reduction so forwarding information rather than the raw data across these tactical sensor networks where data flows are hampered by a disconnected, intermittent and low bandwidth (DIL) operational domain...
In this paper the experimental validation of a novel, modified double scroll chaotic attractor circuit, employed as a true random binary generator (TRBG) for cryptographic applications is presented. The double scroll attractor is modeled on Chua's circuit for nonlinear operation leading to chaotic behavior. The output from the chaotic circuit which is a partially correlated binary sequence is scrambled...
Applications such as situational awareness are becoming more prevalent in highly dynamic tactical mesh networks and are placing high demand on existing RF network capacity. These applications require high aggregate data capacity but have some flexibility in packet by packet latency. Combined radio frequency and free space optical communication within a heavily scintillated atmospheric path behaves...
Based on Universal Mobile Telecommunications System (UMTS) wideband code division multiple access (WCDMA) technology, the mobile user objective system (MUOS) provides a wide range of wireless telecommunications services to the war fighter over geosynchronous satellites. As MUOS is a multiple beam system, it is of paramount importance for the user entry (UE) to select the best beam, which in turn requires...
Military applications often require traffic to be multicast to a group of receivers. It has previously been shown that linear network coding is useful in conjunction with physical-layer multicasting for reliable multicast delivery over fading channels. Superposition coding is an effective way to deliver information to a single receiver over a fading channel. However, we have shown in previous work...
In modern warfare, tactical mobility and environment uncertainty place critical decisions at battalion and below levels. However, the introduction of digital systems (vehicles, soldiers, UAV) enables optimised or new capabilities by taking advantage of informational services. The Phoenix Concept Development and Experimentation (CD&E) lifecycle explores new operational concepts using rapid system...
This paper concerns stability analysis for the packet reservation multiple access (PRMA) protocol extendable for mobile satellite systems (MSSs). This protocol has been widely considered for providing speech and data communications in a terrestrial microcell system. Recently modified versions of the PRMA protocol have been subject of extensive research, with goal of application to low earth orbit...
Multiband tactical communication modems must employ different waveforms to meet various demands in quality and nature of data. Range maximization, high data throughput and power conservation requirements are usually not fulfilled by a single waveform. To effectively deliver tactical multimedia data including coded audio, text, video, map and navigation information using radio, multiple choice of frequency...
We propose a game-theoretic framework for quality-of-service (QoS) aware resource competition among coexisting wireless links in mobile wireless networks. The senders of wireless links use the constant transmit power and then the wireless resources of interest is characterized by time-slot length. Multiple wireless links will use the limited wireless resources through a time-slot competition game...
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